Item duplication

Daylight sensors.
To re-enact: Break a daylight sensor with a Silk Touch Diamond Pickaxe. (Have only tried it with diamond pickaxes with and without ST. Seems to only happen with.)
Obsidian.
To re-enact: Place down an Ender Chest and break with Silk Touch. Ender Chest item drops along with an amount if Obsidian. (So far between 6-10)